Numerical modeling of thermo-mechanical failure processes in granitic rock with polygonal finite elements

This paper considers numerical modeling of intensive heating induced thermo-
mechanical failure processes in granitic rock. For this end, a numerical method
based on polygonal finite elements and a damage-plasticity model is developed.
A staggered scheme is employed to solve the global thermo-mechanical problem. The rock failure is described by a Rankine-Mohr-Coulomb plasticity model with separate scalar damage variables for tension and compression. Consistent tangent operator is derived for this model. Special attention is given to the temperature dependence of the thermo-mechanical material properties of heterogeneous rock. In the numerical examples, the method is first verified with an analytical solution of thermal stresses in a hollow cylinder, and then qualitatively validated with the problems of thermal cracking of concentric cylinders and uniaxial compressive test on rock under elevated temperatures. Finally, the method is applied in novel simulations inspired by the degradation of sauna stones under slow heating-rapid cooling and the comminution by rapid heating-cooling cycles.